Typically, complex interactive devices each have one or more parts that carry out one or more operations. Ideally, the part or parts execute each operation at an optimal or desired level which will vary based on the particular device and the operation. Unfortunately, the part or parts in each device may not always operate at the optimal level.
A variety of factors can effect how well each of the operations is carried out by the part or parts, such as tolerances in one or more operating characteristics of each of the parts. The greater the range in the tolerances in a particular part, the greater the chance that the parts will not execute the operation at the optimal level.
One solution has been to use parts whose tolerances in one or more operating characteristics are within a range that will result in the operation being executed at the optimal level. Unfortunately, parts with the acceptable range for the tolerances are usually the “higher end” or most expensive parts. As a result, the overall cost of the device goes up when these parts are used.
Another solution has been to try and strike a compromise between the performance of the device and the tolerances for the parts needed to achieve an acceptable performance level. This helps to keep the overall cost of the device down, but often results in a device that does not always operate at the optimal level, has lower reliability, and still has a higher cost than may be necessary.